Topic: CB750 Motor rebuild... for dummies

[City Boy]

Paulages.You arnt runnin a flat rate shop.This is your own unit.For a proper rebuild,you want to inspect all components.Proper cleaning also requires full dissassembly.You should reconsider not removing stator and clutch pack.Rock On

[paulages]

Paulages.You arnt runnin a flat rate shop.This is your own unit.For a proper rebuild,you want to inspect all components.Proper cleaning also requires full dissassembly.You should reconsider not removing stator and clutch pack.Rock On

never said i didn't remove the clutch pack, just not the stator. i blasted all the steel plates and installed new friction plates. and i know the cost of my own labor, thanks. 

[City Boy]

10-4.My mistake.

[paulages]

10-4.My mistake.

no prob... if anything, i'm way too anal. i can turn anything simple into a complete rebuild. 

[City Boy]

Now your talkin,me too!

[Terry in Australia]

Hey Paul, the boys were right about the dowels and seals for the cylinder block and head, but I reckon that the big "unidentified" seal is in fact the seal that goes over the big dowel that goes between the two case halves at the front of the engine cases. (joins oil gallery halves from return from oil filter)  If it is, and you've left it out, you better get those spanners out again, or you're in trouble, senor! Cheers, Terry.

G'Day Mark, here's a link to Rusty Riders EBay store: http://stores.ebay.com/Rusty-Riders-LLC 

[paulages]

Hey Paul, the boys were right about the dowels and seals for the cylinder block and head, but I reckon that the big "unidentified" seal is in fact the seal that goes over the big dowel that goes between the two case halves at the front of the engine cases. (joins oil gallery halves from return from oil filter)  If it is, and you've left it out, you better get those spanners out again, or you're in trouble, senor! Cheers, Terry.

G'Day Mark, here's a link to Rusty Riders EBay store: http://stores.ebay.com/Rusty-Riders-LLC 

terry- i'm pretty sure the seal in question is the one behind the stator, as the dimensions match the part listed on the microfiche. the seal that went over the dowel you are talking about was a round profile o-ring if i remember right. this one is square, like the ones on all of the engine covers (shift shaft, kickstart shaft, etc).

[paulages]

yeah, just checked- that o-ring is 18mm X 3mm.

[Terry in Australia]

So you remembered to install that one then Paul? If so, no problemo!

[paulages]

So you remembered to install that one then Paul? If so, no problemo!

yeah. thanks, terry!

[paulages]

fired mine up today and went for a little ride... started second kick, and idles at 1500 RPM perfectly. 

[mystic_1]

Well done!

mystic_1

[Terry in Australia]

fired mine up today and went for a little ride... started second kick, and idles at 1500 RPM perfectly. 

Very nice Paul, but why 1500? Shouldn't it be 900-1000? The GS750 Suzuki I just sold would idle cleanly at 200 (two hundred) RPM with a Martek ignition and stock coils, it was amazing, a lot of old english singles with big flywheels wouldn't do that! Cheers, Terry.

[paulages]

fired mine up today and went for a little ride... started second kick, and idles at 1500 RPM perfectly. 

Very nice Paul, but why 1500? Shouldn't it be 900-1000? The GS750 Suzuki I just sold would idle cleanly at 200 (two hundred) RPM with a Martek ignition and stock coils, it was amazing, a lot of old english singles with big flywheels wouldn't do that! Cheers, Terry.

it's a K6 terry, so it actually idles well now at 1000. what i meant to say is that it roared to life straight into a 1500 RPM idle, which aint bad considering i also rebuilt the carbs and haven't synced yet.

[Terry in Australia]

Ok mate, no worries, I thought I was missing something. While I'm "um-ing" and ah-ing" about Sean's rusty tank (which looks great with the bashed in knee dents, thanks again for the info) I'm gonna pull my F2 engine out and strip the engine, reseal the cases, and fit a K6 cylinder block and head so I can stick it on EBay and make some more space for the Harley Sportster that I want to buy next. I'm gonna try to strip and rebuild the engine in two days, so watch this space! Cheers, Terry.

[mal]

All this talk about what gasket sets has really got me confused. Im at the point of starting the slow rebuild process on my many pieced K2 motor!

Terry in Australia recommended getting gaskets from Cyclex, but they are EMGO gaskets that have been bagged on this thread, as well as others.
Athena gaskets have similarly been criticized.
I have found both Vesrah and Cometic gaskets on the Dynoman website. Trouble is that, from what I have been able to find so far, Cometic dont seem to make a complete set for the SOHC 750. Anyone able to tell me otherwise, and if so a partnumber??? Otherwise, how good is the Vesrah Complete Gasket Set???

Ideally, I would like to get a set of OEM gaskets. Does anyone have any idea if there is such a thing produced (in a kit form) and if so what is the partnumber?
Help. What are the best to use, and where do you get them?
And while your at it, what is the best oil seal set???
Mal
 

[paulages]

All this talk about what gasket sets has really got me confused. Im at the point of starting the slow rebuild process on my many pieced K2 motor!

Terry in Australia recommended getting gaskets from Cyclex, but they are EMGO gaskets that have been bagged on this thread, as well as others.
Athena gaskets have similarly been criticized.
I have found both Vesrah and Cometic gaskets on the Dynoman website. Trouble is that, from what I have been able to find so far, Cometic dont seem to make a complete set for the SOHC 750. Anyone able to tell me otherwise, and if so a partnumber??? Otherwise, how good is the Vesrah Complete Gasket Set???

Ideally, I would like to get a set of OEM gaskets. Does anyone have any idea if there is such a thing produced (in a kit form) and if so what is the partnumber?
Help. What are the best to use, and where do you get them?
And while your at it, what is the best oil seal set???
Mal
 

i have a gasket set at the shop from Z1 and it's definitely not EMGO. i got the EMGO kit from cyclexchange. it's cheap, and has more in the kit than the others (includes the rubber pucks that go over the head studs and some other random o-rings), but the valve cover gasket just plain didn't fit. don't know how they screwed that one up, but it was too big.

[rugger81]

Ideally, I would like to get a set of OEM gaskets. Does anyone have any idea if there is such a thing produced (in a kit form) and if so what is the partnumber?
Help. What are the best to use, and where do you get them?
And while your at it, what is the best oil seal set???
Mal
 

I just bought the oem top end gasket kit for my K7, and it was $70 I believe.  They don't carry the bottom end kit anymore for my model, but I think that was $40.  I don't know what the part number for your kit is, but I had to look mine up online and bring it to my local dealer.  Before when I asked about it, their parts dept said they didn't have a gasket set for my model. 

[Jerry Rxman Griffin aka MuthaF'er]

Let's get Terry to chime in on the CycleX kit. His is a recent purchase. I thought they were doing their "own" now and didn't think it was Emgo. I guess someone has to make it for them. It's supposed to contain a sooper dooper upgraded head gasket. I know Cometic will make the head gasket and base gasket. Perhaps they could do the others as well.

Rugger - do you have the part number for the top end kit? 

Check out this link for bottom end kit B    06111-300-020    http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&viewitem=&item=200204006486

[upperlake04]

....that have been bagged on this thread, as well as others.
Athena gaskets have similarly been criticized.

 Categorically rejecting Athena gaskets might be unrealistic. My experience with them has been entirely satisfactory. The set was complete and has worked flawlessly for a year and 4500 miles in the 750F3 head. Preparation and attention to detail during assembly is probably as least as important.

[Kevin D]

CycleX was out of stock on the kit when I last checked so I went to Z1 and got the Vesrah kit which is pretty good. IMHO get whatever aftermarket kits you can, use what you can and supplement with Honda parts for whats not there. I'm also of a mind to use genuine parts for critical items - like head gasket, point seal. If you go all Honda you will get killed on all of the orings at $2.50 each (6 on the oil pump, 8 valve covers, etc) - I got the Vesrah kit plus $100 of Honda orings and seals.

Z1 service is also tip-top.

[paulages]

Z1 service is also tip-top.

+1 on that.

[Terry in Australia]

Well I'm not going to bag out the CycleX gasket kit just yet, (yes it is an Emgo) but I did have a problem with the head gasket yesterday, which made me use a new Vesrah instead.

The gasket itself looks really well made, (it's a metal/fibre composite and looks a lot better finished than some other gaskets that I've used) but it appears that the holes for the far left and far right cylinder studs are either too small for the dowels on the later engines, or are slightly misaligned, so when I installed it on the K6 cylinder block, it looked like it was sitting "proud" of the cylinder block in the centre, instead of sitting flush, so my concern was that when I torqued it down, it would scrunch up in the middle causing a leak.

Interestingly, I just laid it on a K0 head, and it's a perfect fit, so there may well be slight differences between the models that we aren't aware of? Re: the cam cover gasket, mine fits perfectly, and I'm not going to insult Paul and suggest that he had it upside down, but I have actually done that once before, so it's easy to do. The rest of the gaskets all fit fine, and look like good quality too. I'd certainly buy another one, as Uppy says, preparation is very important, and I never thought the OEM gaskets were that good anyway. Cheers, Terry.  

[paulages]

Well I'm not going to bag out the CycleX gasket kit just yet, (yes it is an Emgo) but I did have a problem with the head gasket yesterday, which made me use a new Vesrah instead.

The gasket itself looks really well made, (it's a metal/fibre composite and looks a lot better finished than some other gaskets that I've used) but it appears that the holes for the far left and far right cylinder studs are either too small for the dowels on the later engines, or are slightly misaligned, so when I installed it on the K6 cylinder block, it looked like it was sitting "proud" of the cylinder block in the centre, instead of sitting flush, so my concern was that when I torqued it down, it would scrunch up in the middle causing a leak.

Interestingly, I just laid it on a K0 head, and it's a perfect fit, so there may well be slight differences between the models that we aren't aware of? Re: the cam cover gasket, mine fits perfectly, and I'm not going to insult Paul and suggest that he had it upside down, but I have actually done that once before, so it's easy to do. The rest of the gaskets all fit fine, and look like good quality too. I'd certainly buy another one, as Uppy says, preparation is very important, and I never thought the OEM gaskets were that good anyway. Cheers, Terry.  

it was a difficult fit around those dowels for sure terry, but it did fit. i can't help but wonder if there are some inconsitencies in the kits?? does you valve cover gasket fit?

[Kevin D]

 I'm continuing with my rebuild, waiting for parts to put cases back together. The cases, cylinder and head painted up nicely, better than I expected. I used VHT and baked 'em in the oven while my wife was away .
 I honed the cylinders last night and that went OK too. I also started with valve lapping but it didn't go as well. The darn suction cup won't stay fastened to the twist stick. I guess thats a hazard of working with cheap tools. I don't really know what I'm doing either (a bigger problem ). I have 120 and 280 grit compound. I've smeared a little compound on the valve and then gave it a minutes worth of twisting while applying light pressure to the stick. I used the coarse and then the fine but didn't see much difference.
 Compression was good before I started this rebuild, I haven't done anything much to the valves or seats - yet - to change that. I don't plan on having the valves or seats recut. Am I wasting my time with this lapping compound?

 I'm hoping this rebuild will last a lifetime, but maybe I'll have it apart again for this or that leak. Terry, I wish I could do it in two days, but thats just not gonna happen for me. I see the drag racers overhaul their engines between heats and I'm in awe.
 I'm not in a hurry, although we have some serious snowmelt going on here. One of the nice things about a Michigan winter is a lotta time to work on the CB. I'm thinking about spring, and my target completion date of April 15th, one month away.